When an organic polyisocyanate is reacted with a polyether polyol to produce a polyurethane composition, various components are introduced into the system in order to adjust the physical properties of the resulting polyurethane composition. For example, if a cellular product is desired, water or an appropriate blowing agent is added to the polyurethane reaction mixture. In order to adjust properties of various polyurethane compositions such as the tensile strength, elongation, tear strength, flexibility, the softness or hardness of the resulting composition, or the color, various other additives are used. Often the addition of an additive to improve one particular property results in the degradation of other properties of the polyurethane composition. For instance, an additive which increases the tensile strength of a solid polyurethane composition, such as various fillers, may result in a decrease in the elongation of the resulting polyurethane composition. Therefore, it is necessary to achieve a balance of properties for a given use.
Solid polyurethane compositions have found usefulness in gaskets, sealants, floor coverings, and the like. More recently, with the advent of molded, rigid plastics, it has become desirable to provide a flexible polyurethane mold for use in the place of the more expensive silicone-type molds currently being used. In order for a polyurethane composition to be acceptable for this use, it must be soft and flexible, yet have good tensile and tear strength so that the mold does not become unusable after a short period of time due to tears or splits in the mold material. Heretofore, polyurethane compositions have not been acceptable for this purpose.
Polyurethane compositions generally in use as floor coverings are systems dissolved in a solvent which are moisture-cured by the atmosphere after application on the floor. These floor coatings have been found to suffer considerably from "bleed through", especially when placed on a substrate which had previously been covered with some other type of floor covering. While there are some single component floor coatings (i.e., solvent types), these have been found to be lacking in one or more of the desired properties for an acceptable floor coating. To be an acceptable floor covering composition, it is desirable that the elastomer be strong, scuff-resistant and yet flexible enough to conform to shifts in the floor.
With the widespread use of foam crash pads in automobiles and the like, it has become desirable to develop a crash pad with a tough scuff-resistant skin which is integral to the foam of the crash pad itself. Previously, it was necessary to line the mold in which the crash pad was to be cast with a decorative coating such as vinyl and the like in order to achieve the strength and scuff-resistance necessary for the pad, and yet maintain an attractive appearance of the crash pad itself. Previous attempts at producing a polyurethane foam crash pad having an integral skin which would meet these qualifications have met with considerable difficulty and disappointing results.
The advantages and objects of our invention will be apparent to those skilled in the art, in view of the aforementioned background, the following discussion and accompanying examples.